State of the art side-emitting light emitting diode devices, LED devices, are commonly used in mobile backlighting applications. The basic structure of a side-emitting LED device in prior art is a substrate with a LED chip and electrical connections, a light guide which is provided with a reflecting structure or top coating which reflects light emitted by the LED chip within the light guide such that the emitted light exits the LED package through a side surface thereof.
US 2006/0273337 A1 discloses a side-emitting LED package and a manufacturing method thereof. The side-emitting LED package comprises the basic structure as described above with the light guide constituted by a moulded part having an upper surface with a centre thereof depressed concavely, which upper surface covers and protects the substrate and the light source. Furthermore, the upper surface is covered by a reflection layer. The reflection layer causes light emitted by the light source to reflect sideward from the moulded part which forms a light transmitting surface in the side directions with reference to the substrate.
The light that exits a side surface of a prior art side-emitting LED as exemplified above, often has an uneven angular distribution. One solution for solving this problem is proposed in the prior art document US 2006/0239000 A1, which discloses a side-emitting LED package in which two individual side-emitting LEDs of basic structure are mounted head-to-head to complement the beam spread from each individual side-emitting LED. However, the mounting of the individual side-emitting LEDs involves mechanically complicated and space consuming constructions.